[Mimedefang] SendmailMacros, greylisting and filter_recipient

[Michael Faurot]

I recently came across David Skoll's code for implementing greylisting[1]
and was able to get that working with my local Sendmail/MIMEDefang
configuration several days ago.  This is a really cool little trick and
has been working quite well in reducing the amount of spam that comes in.
Thanks!

In the course of monitoring the greylist activity and making local
tweaks, I've come across the issue of SMTP authenticated users, and how
to get this code to ignore them.  Having run into the situation of how
to exempt SMTP authenticated users previously, with respect to
SpamAssassin, I added some logic to use $SendmailMacros{'auth_authen'}
to the filter_recipients() function.  After some research[2] through the
list archives, I discovered this won't work because SendmailMacros aren't
available within filter_recipient().  Quoting David Skoll's message,
regarding why this capability is not available:

	No particular reason, other than efficiency.  If you need
	this capability, don't do the relay check in filter_relay,
	filter_sender or filter_recipient; do it in filter_end.  It's more
	expensive, because that only happens after the whole message is
	received, but it works.

Any chance of that changing that?  Obviously it's most efficient to do
the greylisting within filter_recipient() so as to avoid bringing in
the whole message body.  With respect to efficiency of SendmailMacros
in filter_recipient(), how about making that a user selectable option?
As in the default configuration would not include SendmailMacros in
filter_recipient().  If that feature is needed then perhaps some type
of runtime or compile/build time option can be implemented to make
this available?  Given some other messages[3][4], this does appear to
be desirable feature to other people as well.

[1]: http://lists.roaringpenguin.com/pipermail/mimedefang/2003-September/016663.html
[2]: http://lists.roaringpenguin.com/pipermail/mimedefang/2002-December/012774.html
[3]: http://lists.roaringpenguin.com/pipermail/mimedefang/2003-June/015206.html
[4]: http://lists.roaringpenguin.com/pipermail/mimedefang/2003-June/015207.html